Pneumonia lung infection , definition , its causes and treatment

Pneumonia lung infection , definition , its causes and treatment
respiratory diseases

A pneumonia lung infection is an inflammation which is usually caused by an infection with bacteria, viruses or fungi of the lung tissue. It is associated with symptoms such as a cough, fever and dyspnoea. In young, otherwise healthy people, pneumonia generally heals completely again. In elderly, chronically ill or immunodeficient persons, lung inflammation can lead to death. Read all the important facts about the causes, the treatment and the prognosis for lung inflammation. 

Pneumonia Symptoms


Pneumonia Lung inflammation: description 

Pneumonia Lung inflammation (pneumonia) is an inflammation of the lung tissue. It is caused by infectious agents such as viruses or fungi – but most often by bacteria. More rarely is pneumonia caused by the inhalation of toxic substances or by a misregulation of the immune system. Almost half of all pulmonary infections in young patients are attributed to the bacteria type Streptococcus pneumoniae (pneumococci).

Many of the bacteria responsible for pneumonia also occur in the oral cavity. However, if these germs enter the respiratory tract, lung inflammation can develop. It is also possible to infect humans by droplet infection. In elderly persons, children or patients with a weakened immune system, pulmonary infections are particularly dangerous and can be fatal.

Pulmonary infections are usually associated with typical symptoms of the disease such as fever, cough and a general feeling of discomfort. The elderly often have pneumonia without a cough, which makes pneumonia more easily overlooked. If viruses are the trigger, usually the first few days of the lung inflammation without fever.

Lung inflammation can be distinguished in various aspects. The correct classification is important, among other things, to choose the right treatment.

The distinction between primary and secondary pneumonia lung infection:

By pneumonia definition, the primary is distinguished from the secondary pulmonary inflammation. If a healthy person does not have a major health risk factor in a lung inflammation, then medical doctors speak of a primary pulmonary inflammation. In the case of secondary pulmonary inflammation, however, a factor promoting the disease (such as asthma, COPD, heart failure, etc.) or a specific triggering event is present

Distinguishing ambulatory and nosocomial pneumonia

It is crucial to choose the right therapy, where a person with a lung inflammation presumably stuck. In different places (at home, nursing home, hospital, etc.) there are different pathogens, for which other antibiotics are used for the treatment of lung inflammation. Therefore,

Outpatient pneumonia

An ambulant acquired pneumonia (CAP, English for community-acquired pneumonia) is acquired outside the hospital. These include pneumonia, with which someone is infected in retirement or nursing homes. If the inflammation of the lungs spreads in the body, doctors speak of severe pneumonia (SCAP). In a SCAP, life-threatening complications such as a blood poisoning sepsis,) or organ failure can lead to death. It is therefore potentially life-threatening and requires a complex therapy.

Nosocomial pneumonia

Hospital-acquired pneumonia (HAP) is hospital-acquired pneumonia that develops more than two days after admission or within 14 days of discharge. In hospitals, antibiotic-resistant germs are increasingly finding their treatment is often difficult.

Differentiation typical and atypical pneumonia

Lung infections can also be classified according to their symptoms. Doctors refer to a “typical pneumonia” when the classic symptoms of pneumonia such as a productive cough (= with sputum), fever and typical findings in the X-ray and physical examination showed.

An “atypical pneumonia”, also called “interstitial pneumonia”, occurs when the pulmonary arteries (alveoli) are not affected by the inflammation, but the tissue between the alveoli and the blood vessels (interstitium). Atypical pneumonia is characterized by a creeping, protracted course and is caused by other pathogens than atypical pneumonia. About 20 percent of all occurring pneumonia are atypical pneumonia.

Lung inflammation in children

Pulmonary inflammation is the most common form of the respiratory disease in childhood. Here you can find out more: Pneumonia in children.  

Pneumonia: causes and risk factors

Usually, pneumonia is caused by an infection. The pathogen spectrum of pneumonia includes:

  • bacteria
  • virus
  • mushrooms
  • parasites

Most cases of lung inflammation are caused by bacteria. Also, viral pneumonia is not uncommon. In contrast, pneumonia caused by fungi usually affects only people with a poor general condition and a weakened immune system. Parasitic pulmonary infections are rather rare and are more likely to occur in immature persons or travellers in tropical countries.

Other causes of lung inflammation can be:

  • Corrosive irritants such as inhaled gases, foreign substances
  • Radiotherapy
  • Inhalation (aspiration) of gastric contents (aspiration pneumonia)
  • Hereditary diseases such as cardiac insufficiency (cardiac insufficiency) lead to (oedema) in the legs, which can promote pulmonary inflammation (congestive pneumonia).
  • In rare cases, pneumonia can also be caused by pathogens that enter the lungs from other sources of inflammation in the body (for example, in the case of bone inflammation.

The following groups of people are considered to be particularly at risk for pneumonia:

  • Older and weakened people
  • Chronic patients: especially patients with heart disease, people with chronic bronchitis or diabetes mellitus.
  • People whose body’s defences are significantly weakened (eg in HIV infections)
  • People who take medicines that reduce the body’s defences (eg immunosuppressants or cytostatics)
  • Alcoholic people
  • Smaller children

Atypical pneumonia: causes

The most frequent triggers of atypical pneumonia are mycoplasmas, chlamydia, rickettsiae and legionellae (all bacteria). Mycoplasma pneumonia is common in community settings such as schools, homes or barracks. Chlamydia causes pulmonary infections caused by the genus Chlamydia pneumonia, which is transmitted exclusively from person to person. Legionella is found mainly in standing, warm or hot waters. These can be lakes, showers, air conditioning or ventilation systems, hot water boilers or heaters. Legionella pneumonia also causes confusion, lethargy, and diarrhoea in addition to the familiar symptoms.

Special pneumonia: pneumocystis carinii pneumonia

Pneumocystis pneumonia is a special form of pneumonia. It is triggered by a fungus, Pneumocystis jirovecii. Healthy people are not affected by the infection. Pneumocystis carinii pneumonia primarily affects people with immune system weakness, and in most cases is the first sign of HIV infection.

Is pneumonia contagious?

Lung inflammation can be contagious. In pneumonia caused by viral or bacterial agents, pathogens are spread through the air due to coughing or sneezing and can infect other people (droplet infection). How it comes to pneumonia, however, has no effect on the course and severity of the disease. The course depends mainly on the health status of the person concerned and the early onset of therapy. 

Lung inflammation: examinations and diagnosis


To diagnose pneumonia, the attending physician will first record the history of the patient (, asking in particular about past and existing illnesses. In addition, the doctor will ask you about the current complaints. Typical questions of the doctor could be:

  • Do you have a cough? If so, is it dry or with expectoration?
  • Have you noticed chills or fever in the last few days?
  • Do you have drowsiness or a sense of tightness in the chest area?
  • How are you general, do you feel weak and tired?

This is followed by a physical examination, in which the physician tries to detect the densification of the lung tissue (typical of pneumonia) by eavesdropping with the stethoscope or tapping. When listening to the lung auscultation, certain breathing sounds, such as a rattle sound, indicate signs of a lung inflammation. These breath sounds are caused by the compression of the lung tissue and the mucus in the airways.

In an X-ray examination, the extent and location of the inflammation can be determined. Inflamed spots are visible in the X-ray image as shading or condensation, which appear brighter than their surroundings.

If there is a so-called cold pneumonia, the diagnosis is more difficult, since in this form of pneumonia no fever occurs. It is often confused with a common cold.

Diagnosis: Atypical pneumonia

Symptoms of atypical pulmonary inflammation are similar to those of the flu, so the diagnosis is more difficult. Here only one radiograph shows exactly whether and to what extent inflammation of the lung is present. In special cases, (CT) may also be necessary. Legionella can be detected in the urine test.


Pneumocystis carinii pneumonia also complicates the diagnosis. No typical noise can be detected when the lung is heard, and the chest radiograph shows no abnormalities. A safe diagnosis can only be made with the help of a bronchial lavage. A long, thin tube (bronchoscope) is inserted into the lower airways via the mouth. This tube is used to rinse the lung with saline solution, which is then aspirated into a tube. The exciter can be detected in this filtrate 

Lung inflammation: treatment


The treatment for inflammation of the lungs depends on the cause of the inflammation, the age of the patient and possibly existing accompanying or pre-existing diseases. It covers both medication and general treatment.


In almost all cases of inflammation of the lungs, treatment with antibiotics is necessary, since pneumonia is usually caused by bacteria. Antibiotics are often also prescribed for the prevention of viral infections. This does not counteract the viruses, but one prevents an additional infection with bacteria (superinfection). Inform your doctor if they were abroad up to three months before the onset of the disease. Pathogens from other countries sometimes require a different treatment. You should also inform your doctor if you are allergic to antibiotics.

Antibiotics may be administered in tablet form (orally) or as an (intravenous, iv), depending on the patient’s health. The treatment takes an average of seven days but can be prolonged or shortened depending on the individual’s initial state. If the pathogen is not yet known and the physician suspects that problem germs are behind the infection, several drugs are combined to expand the spectrum. The general measures include bed rest and physical protection. Due to the fever, the fluid requirement is increased, which is why sufferers need to drink a lot. Young people without concomitant illnesses can usually be treated at home.

Treatment in the hospital is necessary if:

  • The inflammation captures large parts of the lungs.
  • Severe symptoms occur.
  • The patient has a high age.
  • An immunodeficiency or poor general condition exists.
  • Complications (such as blood poisoning or pleurisy).
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